Magnetic devices, which utilize giant magnetoresistive effects, are ubiquitous in nowadays memory systems [1]. Semiconductor devices on the other hand are the building bricks of information processing systems and Si based devices are in almost every processor used now. Integration of memory and processing onto a single chip has been the driving force for the development of magneto-electric materials and devices [2]. Furthermore, programmable logic devices have been proposed to have many advantages including higher speeds compared to application specific logic devices [3]. For example, field programmable logic gives the user versatility by providing the advantage of logic that is tailored to specific uses while in the field. Further developments of a field programmable logic would be to add an additional functionality of making a chip like that reconfigurable while it runs. A logic device that can be controlled by sending instructions to change each gate while the device is in operation could achieve program specific reconfiguration. The added advantage of using a non-volatile system is the possibility of combining logic and memory on a single chip and thus will eliminate the need for magnetic heads [4].
InMnAs, developed by the inventors has a Curie temperature of 330K [5]. Optical measurements have shown that the material has sp-d exchange which leads to the spin splitting of its valence and conduction bands. InMnAs based diodes have shown giant magnetoresistance and a magnetoresistance as high as 2600% was measured at 18 T and 300K [6]. The material has also been used to fabricate the world's first magnetic junction transistor and magneto-amplification effects were demonstrated at room temperature [7]. The advantage of using a magnetic semiconductor based device is the ease of fabrication, integration with present day electronics and the inherent speed advantage. It would gain a great deal of industrial and technological relevance if programmable logic devices utilizing magnetoresistance of InMnAs based diodes could be available.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.